This invention relates to a method for the conversion of a heavy hydrocarbon oil into a light hydrocarbon oil using a fluid catalytic cracking technique.
While there are increasing demands for light hydrocarbons, petroleum crude produced is now becoming heavier and heavier. In this circumstance, the establishment of effective techniques for converting heavy hydrocarbon oils into light hydrocarbon oils is strongly desired.
There is known a fluid catalytic cracking (FCC) method which has been developed for the production of light hydrocarbon oils such as gasoline and light cycle oil from heavy distillates such as gas oil and vacuum gas oil. The FCC method, in which a zeolite catalyst such as refractory inorganic oxide composited with crystalline aluminosilicate (zeolite) is generally used as the catalyst, has not been adopted for the conversion of heavy hydrocarbon oils containing a residual fraction with a boiling point of 538.degree. C. or higher. This is because the heavy hydrocarbon oils contain a large amount of metals such as vanadium, nickel, iron and copper and carbon residue which cause the deactivation of the catalyst, resulting in the reduction of the yield of valuable fractions such as gasoline and light cycle oil and the increase of the yield of dry gas fractions such as hydrogen and C.sub.2 lighter hydrocarbons and coke.